Aims: Patients having conduction disease and indications for a standard pacemaker implantation are treated with right ventricular (RV)-based pacemaker therapy. The aim of this study was to investigate echocardiographic and clinical effects of RV and left ventricular (LV)-based pacing in patients with standard pacemaker indication and LV dysfunction.
Methods and results: Thirty-nine patients with symptomatic bradycardia due to sinus or atrioventricular nodal dysfunction and having absolute standard pacemaker indication, low LV ejection fraction (EF) (35-50%) and QRS duration <120 ms were included in the study. Pacemaker properties, echocardiographic, and clinical results were evaluated in both patient groups after a long-term follow-up period. A significant increase in LVEF (left ventricular ejection fraction) was observed in left pacing group (from 37 +/- 10 to 41 +/- 9%, P < 0.01) and a statistically significant decrease in right pacing group (from 40 +/- 7 to 37 +/- 10%, P < 0.05). Intraventricular asynchrony was not developed in left pacing group, whereas significant asynchrony occurred in 73% of patients in right pacing group. New-onset interventricular asynchrony was detected in three and 10 patients in LV pacing group and RV pacing groups, respectively. Intraventricular and interventricular asynchrony was found together in seven of RV lead implanted patients. Although statistically insignificant, LV end-diastolic diameter was increased (from 56 +/- 6 to 60 +/- 6 mm) and EF was decreased (from 39 +/- 7 to 33 +/- 9%) in these patients (P = 0.07). During follow-up, 40% of patients in RV pacing group were admitted to the hospital due to heart failure in contrast to LV pacing group.
Conclusion: LV-based pacemaker implantation is more suitable for patients having standard pacemaker indications and LV dysfunction even in the absence of ventricular asynchrony.